OBJECTIVES: 1. To investigate further the details of the interaction of helix-destabilizing (unwinding) proteins with DNA. These studies will be related to catalysis of DNA renaturation, DNA replication and recombination. R loop formation driven by helix-destabilizing proteins will also be investigated. 2. To investigate the equilibria and kinetics of branch migration with a variety of nucleic acid systems. These studies will be related to nucleic acid renaturation and hybridization mechanisms and to DNA recombination. The effects of base-pair mismatching will also be investigated. 3. To investigate further the renaturation and hybridization kinetics of nucleic acids in tetraalkylammonium halide containing solvents with emphasis on mechanisms and acceleration of hybridization rates. Acceleration of rates on solid supports will also be attempted. 4. To continue the development of kinetic extraction procedures for isolation of genes based on insertion or deletion mutations. These studies will be applied to transformed mammalian cells. Improved methods for the detection, identification and characterization of small quantities of nucleic acids will be sought.